An isc-dhcp security update has been released for Debian GNU/Linux 11 to address several vulnerabilities.

DSA 5251-1: isc-dhcp security update

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Debian Security Advisory DSA-5251-1 security@debian.org
  https://www.debian.org/security/ Salvatore Bonaccorso
October 06, 2022   https://www.debian.org/security/faq
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Package : isc-dhcp
CVE ID : CVE-2022-2928 CVE-2022-2929
Debian Bug : 1021320

Several vulnerabilities have been discovered in the ISC DHCP client,
relay and server.

CVE-2022-2928

It was discovered that the DHCP server does not correctly perform
option reference counting when configured with "allow leasequery;".
A remote attacker can take advantage of this flaw to cause a denial
of service (daemon crash).

CVE-2022-2929

It was discovered that the DHCP server is prone to a memory leak
flaw when handling contents of option 81 (fqdn) data received in
a DHCP packet. A remote attacker can take advantage of this flaw
to cause DHCP servers to consume resources, resulting in denial
of service.

For the stable distribution (bullseye), these problems have been fixed in
version 4.4.1-2.3+deb11u1.

We recommend that you upgrade your isc-dhcp packages.

For the detailed security status of isc-dhcp please refer to its
security tracker page at:
  https://security-tracker.debian.org/tracker/isc-dhcp

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at:   https://www.debian.org/security/